Add usePrevious hook.

src/Main.ts

@@ -9,6 +9,8 @@ export { default as useMediaMatches } from './useMediaMatches';
 export type { MessagingCallback, MessagingCallbacks, MessagingOptions } from './useMessaging';
 export { default as useMessaging } from './useMessaging';
 
+export { default as usePrevious } from './usePrevious';
+
 export { default as useRerender } from './useRerender';
 
 export { default as useStoredState } from './useStoredState';

src/usePrevious.ts

@@ -0,0 +1,14 @@
+import { useEffect, useRef } from 'react';
+
+/**
+ * Accepts a value, stores it, and then returns it on the next render.
+ *
+ * @param value - The current value.
+ * @returns the previous value, or undefined if this is the first render.
+ */
+
+export default function usePrevious<T = any>(value: T): T | undefined {
+	const ref = useRef<T | undefined>(undefined);
+	useEffect(() => { ref.current = value; }, [ value ]);
+	return ref.current;
+};